Dural Venous Sinuses and Meninges (fellow)

Question 1

What are the cranial meninges made of?

Answer 1

Three dense regular connective tissue layers that separate the soft tissue of the brain from the bones of the cranium

Encloses blood vessels to the brain

Contain and circulate CSF

Form some of the veins that drain blood from the brain

Question 2

What are the layers of the scalp and meninges superficial to deep

Answer 2

Scalp

Skull

Periosteal Dura Mater

Meningeal Dura Mater

Arachnoid Mater

Subarachnoid Space

Pia Mater

Cerebral Cortex

Question 3

Describe the Dura Mater

Answer 3

Composed of two layers

• Periosteal layer, attached to bone
• Meningeal layer, deep to periosteal layer

Strongest layer of the meninges

These two layers are typically fused except in specific areas where the two layers separate to form large, blood-filled spaces called dural venous sinuses.

Question 4

Falx Cerebri

Answer 4

Dural venous septa, separating the left and right hemispheres of the cerebrum

Question 5

Describe the Arachnoid Mater

Answer 5

• Located immediately internal to the dura mater
• The part made of collagen and elastic fibers is called the arachnoid trabeculae (spider’s web)
• Between the arachnoid and the dura mater is the subdural space
• Deep to arachnoid is subarachnoid space

Question 6

Describe the Pia Mater

Answer 6

Innermost menix

Thin, delicate layer of CT adhering to the brain tissue, following the contours of the surface

Question 7

What is the cranial dural septa

Answer 7

the meningeal layer of the dura mater extends as flat partitions (septa) deep into the cranial cavity at four locations called cranial dural septa

Question 8

What does the dural septa function as?

Answer 8

partition the brain and provide support and stabilization to the whole brain

Question 9

What are the four cranial dural septa?

Answer 9

Falx Cerebri

Tentorium Cerebelli

Falx Cerebelli

Diaphragma Sellae

Question 10

What lies within the cranial dural sinuses?

Answer 10

Dural Venous sinuses:

• superior and inferior sagittal sinuses
• straight sinus
• sigmoid sinus
• transverse sinus

Question 11

Clinical Note

Cavernous Sinus Thrombosis

Answer 11

Sx: high fever, periorbital edema and chemosis, cranial nerve palsies, decreased visual acuity

Dx: CT/MRI

Rx: IV Abx, heparin, surg. consult

Question 12

Describe CSF

Answer 12

clear, colorless liquid that circulates in the ventricles and subarachnoid space

bathes surfaces of CNS and surrounds it

provides buoyancy, protection and stability

Question 13

Production and compostion of CSF

Answer 13

formed by choroid plexus in each ventricle via ependymal cells that originate from the blood plasma

similar in composition to the blood plasma but with more Na, H, Ca and less K.

Question 14

Function of the Emissary vein?

Answer 14

drain from scalp into sinus

Question 15

Function of the bridging vein?

Answer 15

drain cerebral cortex into dural venous sinus

Question 16

Describe the Subdural Space

Answer 16

“potential space”

only seen when something is wrong, like bleeding from the bridging vein into the subdural space or separation of the arachnoid+dura mater after an LP

Note that there are many important arteries in this space (ICA)

Question 17

What are the cranial dural septa separating

Answer 17

Falx Cerebri-separates lobes of cerebrum

Diaphragma Sellae-lies over optic chiasm and pit.

Tentorium Cerebelli-separates cerebrum from cerebellum

Falx Cerebelli-separates cerebellum lobes

Question 18

What is significant about the diaphragma sellae?

Answer 18

overlies pituitary gland and cavernous sinus

Question 19

What is the arterial supply to the meninges?

Answer 19

Middle meningeal artery (frontal and parietal branches)

comes of Maxillary A. off of ECA out of foramen spinosum

Question 20

What is the innervation of the Meninges?

Answer 20

V1-anterior and posterior meninges

V2- mid anterior meninges

V3- outer and middle meninges

C2-3 fibers base/bottom of meninges (floor of posterior cranial fossa)

Question 21

Epidural Hematoma

Answer 21

middle meningeal artery

looks like a convex lens

stops in this shape due to dura adhering tightly to suture lines

Clinical Vignette: hit in side of head over Pterion (weakest) and strike middle meningeal A. Lucid interval followed by acute onset of mental status changes/deteriation

Question 22

Subdural Hematoma

Answer 22

bridging veins

crescent shape

Clinical Vignette: potential space (subdural) is open. Old person falls or MVA (decell/accel. injury) or Shaken Baby Syndrome

common in babies or old people as veins are weaker

Question 23

Subarachnoid hemorrhage

Answer 23

cerebral arteries

spiderweb looking shape over the circle of Willis

Clinical Vignette: “worst headache of my life” may have aura, N/V. Maye see blood on LP. RF include post-menopausal, HTN, polycystic kidney disease, Ehlers-Danlos.

Question 24

Answer 24

Know These

Question 25

The internal carotid a. and the cavernous sinus

Answer 25

ICA is very tortuous and contains these parts:

cerebral-goes up and becomes circle of willis

cavernous-within sinus

petrous-descends

cervical-lowest part

Question 26

Hydrocephalus

Answer 26

When blood is in the subarachnoid space, it is unable to be filtered by the arachnoid granulatum and will cause damage and fibrosis.

This will clog the system and the CSF will accumulate and compress the brain and enlarge the ventricles causing hydrocephalus

note that the sinuses are not covered in the blood brain barrier